Heart for a Heart
by RainbowSerenity
Summary: /Zemyx, AU/ The outcasts always stuck together through studying and scales, but when Demyx's heart problem suddenly takes a serious turn, he's forced to think of the fact that he'll either have to live with Zexion, or, well...WITH him.


Aaaand here we go. My first ever Zemyx fic. –sweatdrops- Hope you guys like it!

**Heart for a Heart**

All his life, Demyx had known he was different than those around him. After all, there was definitely a reason he'd always taken music classes growing up while everyone else in his class had P.E.

He'd found out the reason as soon as he was able to comprehend it, when he was ten years old or so. Demyx's parents explained that he'd been born with two holes in his heart. It was a disease, but not contagious, meaning he could live as normally as possible but couldn't strain himself, which included those dodgeball-filled gym classes.

It was wasn't until he became a teenager that his condition really started to freak him out – his parents began to warn him that he may need open-heart surgery someday, along with a heart transplant. His condition was mostly stable, but it always had that chance of taking a turn for the worse.

However, five years later, it still hadn't. Demyx was eighteen, about to graduate high school, and had and awesome group of freaky friends that couldn't care less that he couldn't handle 'strenuous activity'.

Oh yes, and his Awesome Life also came equipped with an awesome boyfriend.

"Look, here comes Genius-on-Wheels," Axel joked, elbowing Demyx in the side.

Speak of the devil.

Demyx felt a grin split his face as he walked up to Zexion and gave him a quick peck on the lips before walking alongside his wheelchair back towards their freaky friends.

Zexion pretty much _was_ a 'genius-on-wheels', as Axel had dubbed him. Like Demyx, Zexion had been born with a physical medical condition. His was called _muscular dystrophy_, which caused his muscles to slowly deteriorate. Because of it, he'd never been able to walk well, so he used a wheelchair to get around.

What Zexion lacked in body, though, he definitely made up for in brains. He'd been at the top of his class pretty much his whole life. Everybody thought his GPA was like four-point-two, the record for a single student (Demyx knew better; it was really four-point-three unweighted), and he probably could've graduated _college_ by now, but he said he'd wanted to graduate with Demyx and their friends.

Man, when they all _did_ graduate, it was bound to be one insane ceremony. Without much 'strenuous activity', of course.

Roxas practically jumped on Zexion when he had wheeled himself over. "Zexion, finally! Do you have last night's lit homework? I can't find mine anywhere!"

Zexion raised an eyebrow. "'Can't find it' or 'didn't do it'?"

"Oh, we did do it," Axel chimed in, clapping a hand on Roxas's shoulder. "Like four times. I'm surprised you're walking in a straight line this morning, Shorty."

_"Axel!"_ Roxas hissed, going bright red. Everyone laughed, except for Zexion, who just smirked a bit.

"Sorry, Roxas. You know my policy on lending homework out."

The blond groaned. "I'm gonna _faaaail._"

Larxene suddenly spoke, like she absolutely couldn't help but offer her opinion – which was probably the case. "Y'know, Zexy, I bet you'd let _Demyx_ copy your homework." Marluxia nodded in agreement.'

"Well, yeah," Demyx said before Zexion could open his mouth. "I have better hair than Roxas."

Everyone laughed again, even Zexion, although he merely chuckled with an amused glint in his uncovered eye.

--

Demyx loved his fourth period. It was right after lunch, so he was always in a good mood from hanging out with his friends. Even better, it was his music class. Even better-better, Zexion was in it.

Well, technically it was supposed to be his study hall, but it was tough enough to get into the library even _with_ the wheelchair-accessible ramp. So Demyx had had a few chats with the music instructor and boom, instant Zexion.

It always made Demyx smile to see Zexion in here because as the slate-haired boy often said about himself, he 'couldn't carry a tune in a bucket' - which, actually, was oddly true most of the time. However, ever since being put in the class, Demyx had seen a lot of improvement at Zexion playing the keyboard.

The keyboard was a perfect choice for Zexion. It could easily fit on his lap, he didn't need his feet like he would've for a normal piano, and he was the only one in the class who took that instrument. Demyx, of course, played his sitar. The music teacher often joked that the class would be lost without them once they graduated, as the class had never had a keyboard or sitar player amongst them. Heck, half of the kids in the class hadn't even _known_ what a sitar was before Demyx came along.

The blond glanced over at Zexion and smiled to himself as the other tried to remember and play his scales. They'd always been the two oddballs out, even before they had gotten together. He couldn't imagine why he _wouldn't_ have, but Demyx thanked every nerve in him that had the guts to talk to 'the wheelchair kid' that had randomly appeared in his P.E. class...thirteen months, nine days, and six hours ago. A few minutes of random chatting (mostly on the blond's part) later they knew about each other's physical problems, and later that period, Zexion had ultimately gained some lifelong friends. About a month after that, there was one very awkward conversation – again, mostly on Demyx's part - that led the two to start dating.

Luckily, neither of their parents seemed to care (they were probably just overjoyed that their special little boys had found someone to love in spite of being so different), so all was well with the world. Well, Axel sometimes made fun of them, but that was Axel. He made fun of everybody, including himself.

Demyx suddenly sighed happily and automatically played his scales, hoping to nonchalantly demonstrate to his boyfriend how to do it without getting spotted by the teacher, but quickly stopped and frowned when he saw Zexion massaging one of his shoulders, looking pained. He gently poked the slate-haired boy's arm. "You okay?"

Zexion nodded. "Don't worry about it."

"Well, I kinda _have_ to, Zexy. That's my job."

Zexion rolled his eyes. "Get back to work."

--

Before he'd met Zexion, Demyx had never really cared too much about studying or getting really high grades. He paid attention in class, took some half-hearted notes, and hoped for the best.

However, now it was a completely different story. Every day after school (except Fridays, which were reserved for the whole gang to watch dirty movies at Axel's place), Zexion and Demyx did their homework and studied like mad without fail. Maybe that was one reason Demyx's parents didn't care that he was dating Zexion; the blond had never had such high grades in his life.

"Lessee...Proteus, Triton, and...Nimrod? No..." Demyx muttered.

"That's 'Nereid'," Zexion supplied, looking over the top of his laptop. "Why would they name one of Neptune's moons 'Nimrod'?"

"To confuse me."

"Not everything is out there to confuse you."

"Yes it is." Demyx munched on a cheese puff. "If it wasn't for you, I wouldn't even _know_ the moons of Neptune."

"But isn't that something out of fourth grade science?"

"Noooo. I don't even think half of the people in my fourth grade class even knew that other planets had moons, much less memorized their names."

"Hmph."

Silence filled the room, except for Demyx chewing on some more cheese puffs. Not even ten minutes later, however, he abandoned his astronomy textbook and stood up, stretching.

Zexion didn't look up from his laptop. "Taking a break?"

"I have to or my brain will explode." He wandered over to Zexion and wrapped his arms around the slate-haired boy's thin shoulders. "C'mon, Zexy. Let's watch TV or play some video games or even just stare at the ceiling. I'm boooored."

The typing continued. "Sorry Dem, I really need to get this paper done. And..." He paused when the blond starting nibbling on his earlobe. "Demyx, what do you think you're doing?"

"Study break," was the reply.

Zexion didn't have an answer for that – well, a coherent one, anyway – as Demyx continued a trail of kisses down his neck and towards his shoulder. He felt the blond smile against his skin and frowned a bit. "What?"

"I know your physical therapist tells you to work out your muscles whenever you can, but being this tense isn't helping." Demyx started massaging Zexion's shoulders the way the physical therapist had taught him to. "You can relax a _little_ bit. And it's not the end of the world if you put off that paper for ten minutes, either."

"Yes it is," Zexion muttered, but he didn't even bother to fight back more than that. He had always hated the pity he would sometimes get from people when they found out about his condition, but Demyx had never been like that, probably because he was in such a serious state himself. Demyx was the way he was towards him because he always _wanted_ to be, not because he felt he _had_ to be. It was a blessing for someone to see him as _Zexion_ and not just 'the kid in the wheelchair.'

Demyx continued his ministrations on Zexion's shoulders, only stopping when the other suddenly flinched and rubbed at his arm. The blond frowned. "You okay?"

"Yes, I'm fine. Just a...muscle spasm, I suppose."

"Well, tell one of the doctors about it if it gets any worse, okay?"

"...Yeah."

"I _mean_ it, Zexy."

"Yes, I will."

"Good." Demyx hummed and continued the massage without noticing that Zexion still hadn't let go of his arm.

--

The two had never needed that many words – well, at least Zexion didn't, anyway. So when almost two months went by and Zexion grew more and more quiet, it didn't arise any suspicion in Demyx at all until the day everyone later called 'Doomsday' reared its ugly head.

It had started out innocently enough. Friends in the morning and again at lunch, with some Roxas begging for homework and dudes hitting on Marluxia in between – then came fourth period.

Demyx frowned, watching as Zexion struggled to life his keyboard onto his tray. Dumb Zexion, being too proud to ask for help, even from Demyx. Hmph.

The blond sighed and reached down, grabbing the keyboard and dumping it unceremoniously onto the try. Zexion nodded in thanks, slowly looking up. Demyx frowned. Was something going on that Zexy wasn't telling him? It was so _like_ the slate-haired boy to keep everything bottled inside instead of opening up. It really hurt him. Demyx clutched a hand to his chest. It really _did_ hurt...

His heart began beating wildly. Unbeknownst to him, Zexion was also in pain, clutching his arm again. Why, why _them?_ It was a question they'd always secretly asked themselves, and oddly continued to do so as both of their eyes slid shut and they fell to the floor in a heap.

The music instructor screamed, as did some of the other students before one rushed to call an ambulance. The rest were oddly intrigued. How many other students got to witness two people pass out in one day?

--

Having lived with his heart problem his whole life, Demyx was used to hospitals. He could even recall times like this one where it took him a few moments to realize where he was. Backless, paper-thin gown? Check. Unidentified beeping machines? Check. Extremely flat pillow and equally uncomfortable bed? Double check.

He blinked, trying to remember why the heck he was here. The last thing that crossed his mind was laughing at Axel's awful impression of the popular crowd at lunch, and then...and then...

"Zexion!" Demyx gasped, sitting straight up and ignoring the flash of pain that shot through his body. Zexion had collapsed too – was it serious? Was he at the same hospital? Was he even awake yet!?

Just before the blond was about to rip the IV out of his hand and search the premises for his boyfriend no matter what the consequences, a doctor with an official-looking clipboard wandered in. He flipped through some pages and looked up at Demyx, pleased to see that he was conscious.

"Demyx?"

"Yeah...what – "

The doctor gave a little half-smile that wasn't really humorous. "Your parents have been notified and are on their way, but I'll tell you the story before they get here. I don't know a gentler way to say this, but...your heart had a bit of relapse. If you don't get a transplant soon, you probably won't survive the month."

Silence filled the room, and Demyx secretly started hating this doctor. He'd passed out; had no clue where his boyfriend was or if he was okay; his head was pounding; his hand stung from where the needle of the IV was pinching him; and now he was told that he could quite possibly die very soon unless someone miraculously was an organ donor with a heart to spare – all within the span of about five minutes.

"Uh..."

"I realize it's a lot to take in." The doctor had his nose buried in his clipboard again. Demyx craned his neck to see the dude's nametag. 'Ansem Wise, M.D.', it read. Well, this 'Ansem Wise' could take his clipboard and shove it up his butt. Demyx was in no mood for fake sympathy from stupid, clipboard-carrying M.D.'s. All he wanted to do was find Zexion, get the heck out of this place, and lie on the couch with his boyfriend for the next decade or two.

The doctor was talking again. "Have you been under any unusual amounts of stress lately that could've contributed to this problem?"

Demyx frowned. "No more than usual...although I've been really worried about my, uh, _friend_ Zexion. He's got muscle atrophy, and I think he's been in pain lately and not telling me."

Ansem raised an eyebrow. "Zexion? That boy with the odd hair in front of one eye?"

"Yeah."

"He's here. Well, on the floor above us, to be more precise. I believe he was asking for you. Would you like me to see if he can come down here?"

Demyx stopped hating this Ansem dude. "Yes, please!"

"Very well. I'll be back in a moment." He left the room.

A few minutes of not-so-quiet silence passed. Now that he was alone, the severity of the blond's situation started to sink in. Heart donors were extremely rare, and even if they did find a compatible one in time, there was no guarantee that his body wouldn't reject it. Demyx bit his lip. He wasn't that scared, or even that worried...there was just a weird feeling stirring his gut that he couldn't quite pinpoint.

Ten minutes went by. The door suddenly creaked open and Demyx nearly flew from his bed to see that the visitor was Zexion. The nurse that had brought him smiled at his reaction and quietly left.

Neither of them spoke for a few seconds. Zexion was slumped in one of the hospital's generic wheelchairs instead of his own, which for some reason scared Demyx more than the slate-haired boy's sickly pale face or the way his hands were shaking uncontrollably. Zexion _always_ used his own chair.

"Zexy? What...what happened?"

Zexion swallowed and with a huge amount of effort, wheeled himself closer to Demyx's bedside. He lifted a shaky hand and placed it on the blond's own.

"First of all, I need to apologize. I haven't been completely honest with you."

Demyx blinked. "Huh? Honest about what?"

"I..." Zexion was now looking at the bed, the machines, the IV, pretty much anywhere that _wasn't_ Demyx's face. "Well, my...condition has been steadily getting worse over the past few weeks. I know I claimed I was okay when you asked me, but it really couldn't have been farther from the truth."

"Why'd you lie to me, Zexy?"

"I didn't want you to worry."

"And you passing out while you were supposed to be practicing your stupid scales _wouldn't_ worry me?"

"..."

Demyx let out a huge sigh. "I'm sorry. Scales aren't stupid."

"..." Zexion gave a very slight half-smile. "No...they aren't."

"Why'd you pass out, though? Apparently I did because I had some sort of a 'relapse' or something. And not to worry you or anything because you probably don't need this right now but I'm going to tell you anyway – "

"Dem, just spit it out."

"I need a heart transplant within the month or I'm going to die."

"..."

Once again, not-so-quiet silence filled the room. Finally, Zexion sighed and bit his lip. "I was afraid of that."

"Huh?"

Zexion looked down at his hands. "If I had just told you what was going on, maybe you wouldn't have worried, and you'd be alright..."

Demyx rolled his eyes. "My parents always told me it was bound to happen eventually. I'm just hoping that a donor becomes available, which is kind of morbid since that means someone _else_ would dead, but...I just don't know what to think."

"...There is a donor."

"Wha...what!?" Demyx's heart leapt.

"My...condition has slowly been getting worse," Zexion explained softly. "At my last exam, they said it was only a matter of months before all of my muscles would begin to fail, and I'd be nothing more than a bedridden vegetable until the end." He looked Demyx in the eye. "And you _do_ know that the heart is a muscle, right?"

Demyx's mouth fell open and a horrified look crossed his face. "Zexy, you _can't_ be serious! I can't – you won't – I just..."

"It's the only logical solution. My heart isn't infected yet, but it will be so as long as it's in my body. You need one. It makes sense."

"This isn't _about_ making sense!" Demyx yelled in rage. "Screw logic! I need _you_ more than a stupid heart!"

"Having me around won't keep you alive."

"I..." The blond was at a loss for words. He knew what Zexion was saying made sense. He _knew_ that this was probably his only guaranteed donor. But...why? _Why?_

"I hate you," he finally whispered, giving Zexion a helpless look. "Why are you doing this?"

"My body's never been very useful, so I figured that while I still had a chance, I would make it count for the only person outside of my family who's ever given a damn about me."

"You know that's not true," Demyx mumbled, but he knew what the other meant. "I just...you..."

"And...I've arranged for it to happen tonight."

"What!? Why!? Couldn't you have given me a little time to absorb all of this!?"

"The sooner, the better." Zexion gave a barely audible sigh. "If your body rejects my heart, you'd be placed at the top of the donor list. You know that."

"It won't reject it."

"You don't know that."

"Yeah, I do – because it never has." Demyx leaned forward and flung his arms around Zexion's neck, not even caring about the IV, the pain either of them was in, or the fact that both of their parents and doctors had suddenly come bursting through the room, looking grim. Their mothers were both sobbing uncontrollably.

Zexion tentatively hugged Demyx back, trying not to care about all of the witnesses. He'd never been a fan of PDA, but he figured he could make an exception one last time.

--

Six hours later, papers had been signed and the boys had been separated and prepped for surgery. Demyx was still too numb from the shock of Zexion's decision to be nervous about the actual transplant. He just couldn't grasp the fact that once he woke up from the anesthesia, Zexion would be...gone.

Well, not _quite_ gone. If the transplant was a success (and Demyx had faith it would be; Zexion had never let him down before), Zexion would quite literally live inside of him until the day he died. It comforted the blond a bit to know that they'd always be together, even in the most unusual sense, but...you couldn't kiss a heart, you couldn't cuddle with it, you couldn't do your homework or practice scales with it.

It scared him.

One of the nurses – so many had popped in and out that he'd lost track of their names – suddenly appeared with a small smile. "Hello, Demyx. I'm here to take you in for your operation now."

"Goody," Demyx muttered sarcastically.

The nurse ignored it and helped him out of his bed and into a wheelchair. Demyx wondered if he'd see Zexion on the way.

He did. The slate-haired boy was slumped over; his visible eye half-closed with his hair hanging over the other limply. Demyx's heart raced at the sight.

"Zexion!" he cried, leaping from his chair and racing towards the other, ignoring everyone's raised eyebrows. The blond flung his arms around Zexion, and suddenly not caring who was looking, pulled him in for a long, deep kiss.

"I love you," he murmured under his breath, not even hearing the giggles of the women and the chuckles of the men around them.

Zexion just blinked. "Me too," he whispered, before they were separated and wheeled away.

Demyx held back tears. Maybe now he could handle this surgery.

Maybe.

--

"Mom, seriously, I don't want to go. I don't think he'd want me to."

"Are you sure, honey? I know it's hard, but funerals are a way to have closure, to say goodbye."

"I don't need to say goodbye. Not ever."

"Well...alright. We'll be back later tonight."

Demyx nodded and watched as his mom grabbed her coat and left for Zexion's funeral. The idea to go had never even crossed his mind. To him, Zexion was still very much alive with a healthy, slow beat inside of his chest.

Their friends weren't attending, either. Instead, after he was sure his parents were gone, he called them all up and agreed to meet in front of the school. They were all gathered there twenty minutes later, looking grim. Roxas was leaning into Axel and staring at the ground, his expression the most unreadable.

None of them spoke, not even Axel, which was a first for him. They all just nodded quietly as Demyx pulled his sitar out of its case and began to play right there on the school's front stairs. A lot of Zexion's life had revolved around his studies, so it seemed very fitting.

None of them could say how long they sat there, but the sun had set before Demyx stopped playing and they all wordlessly fell into an awkward group hug. After another moment, Axel slipped an arm around Roxas' shoulders and they bother wandered off; Marluxia and Larxene soon also walked away in separate directions.

Demyx remained there for a long time afterwards. He didn't know what exactly he was waiting for, but it seemed important that he stayed away from everything for awhile.

The moon rose. The blond sighed heavily, when oddly, his heart gave one loud thud against his chest. Five more followed, and then his healthy heart returned to normal.

Demyx smiled and laid a hand on his chest. "Okay, okay, I'll go home and practice my scales."

Zexion would, quite literally, always live on in his heart.

--

I'm a sap. –sob- **Review**, please? I'd very much like some feedback on this. :D


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